Process for upgrading dripolene

ABSTRACT

A PROCESS FOR PROVIDING A HIGH OCTANE BLENDING COMPONENT FOR GASOLINE FROM DRIPOLENE FEEDSTOCKS CONTAINING DIMERS AND CODIMERS OF CYCLOPENTADIENE AND VARIOUS METHYL DERIVATIVES THEREOF BY DISTILLING, CRACKING , AND HYDROGENATING UNDER DEFINED CONDITIONS INCLUDING THE USE OF AN OXYGEN-FREE ATMOSPHERE AND LIMITED RESIDENCE TIMES OF THE DISTILLING AND CRACKING STEPS WHEREBY HYDROGENATED MONOMERS OF THE DIMERS AND CODIMERS ARE OBTAINED IN THE DRIPOLENE THUS UPGRADING IT.

Jan. 29, 1974 E. CAFLISCH ETAL 3,788,979

PROCESS. FOR UPGRADING DRIPOLENE Filed Oct. 8, 1971 United States Patent3,788,979 Patented Jan. 29., 1974 US. Cl. 208-255 10 Claims ABSTRACT OFTHE DISCLOSURE A process for providing a high octane blending componentfor gasoline from dripolene feedstocks containing dimers and codimers ofcyclopentadiene and various methyl derivatives thereof by distilling,cracking, and hydrogenating under defined conditions including the useof an oxygen-free atmosphere and limited residence times in thedistilling and cracking steps whereby hydrogenated monomers of thedimers and codimers are obtained in the dripolene thus upgrading it.

FIELD OF THE INVENTION This invention relates to a process for upgradingdripolene feedstocks to provide high octane blending compoents forgasoline.

DESCRIPTION OF THE PRIOR ART In view of the increased demand for highoctane gasoline arising out of the current feeling that lead, which hasbeen under fire as a pollutant, be reduced in amount or completelyeliminated as a gasoline additive, the art has turned to the problem ofupgrading various feedstocks which have high octane blending potentialin the gasoline field. One such feedstock is dripoline, liquidby-product of a hydrocarbon cracking process for the production ofethylene. For many years the C to C fraction of dripoline has beendistilled off and used as a blending component in the gasoline market,but the C fraction, which makes up about 10 percent to about 20 percentby weight of the dripolene has proved to be of comparatively littlecommercial value in view of its high gum content after distillation,1000 to 5000 milligrams per 100 milliliters, and poor stability, both ofwhich cause malfunction in gasoline engines.

What is known as the 0 fraction (or C dripolene) has potential ingasoline blending because of its make-up, which varies over a widerange, but generally comprises styrenes; indenes; naphthalenes;a'lkylenbenzenes having one or more alkyl side chains each having one tosix carbon atoms; a small amount, if any, of cyclopentadiene and itsmethyl derivatives; dicyclopentadiene and its methyl derivatives; and,on occasion, some 0, compounds. In terms of boiling points, thecomponents have ranged upwards from as low as about 30 C.

A chromatographic analyses of several specific C fractions shows thefollowing compounds to be present in all or some of the fractions:ethynylbenzene, ethylbenzene, m-xylene, o-xylene, p-xylene, styrene,mand p-ethyltoluene, o-ethyltoluene, mesitylene, psuedocumene,o-methylstyrene, mand p-methylstyrene, beta-methylstyrene, indan,indene, C benzenes, tetralin, napthalene, methylindenes,methylnaphthalenes, n-octane, n-nonane, n-decane, cyclopentadiene,methylcyclopentadiene, bicyclononadiene, isopropenylbicycloheptene,dicyclopentadiene, methyldicyclopentadiene, vinylbicycloheptene,dimethyldicyclopentadiene, and allylbenzene.

In spite of the high octane blending potential of the C fraction, itsdisadvantages, i.e., high gum content and polymer formation ondistillation, the attendant fouling of processing apparatus, poorstability, low overall octane values, persistent foul odors, lowvolatilities, and propensity for shortening of catalyst life whenhydrogenated, have been difiicult, if not impossible to overcome, usingknown methods for dealing with same. For example, one method proposed toreduce gum formation in the C fraction was hydrotreatment which is aprocess for reacting hydrogen with some of the known gum formers,conjugated diolefins and styrenes, but this process did not succeed ineliminating the stated disadvantages appreciably and the C fractionremained in the category of a heavy fuel oil.

SUMMARY OF THE INVENTION An object of this invention, therefore, is toprovide a process for upgrading dripolene to the point where not onlythe C to C fraction is useful in high octane gasoline blending, butwhere a high proportion of the C fraction is useful as well byessentially eliminating the heretofore mentioned disadvantages.

Other objects and advantages will become apparent hereinafter.

According to the present invention, gum formation and fouling ofhydrogenation apparatus are essentially eliminated, stability isachieved, and useful high octane gasoline blending components areobtained from dripolene feedstocks containing at least five percent byweight of at least one dimer of the group consisting ofdicyclopentadiene and the methyl derivatives thereof, one codimer formedfrom members of the group consisting of cyclopentadiene and the methylderivatives thereof, or one codimer of the group consisting ofcyclopentadiene and the methyl derivatives thereof with conjugateddienes having 4 to 10 carbon atoms by a process comprising the followingsteps:

(a) (i) introducing the feedstock into a distillation zone wherein thetemperature at the bottom of the zone is in the range of about 40 C. toabout C. to provide an overhead distillate which includes essentiallyall of the dimers and codimers defined above and present in thefeedstock; or

(ii) introducing the feedstock into a cracking zone wherein thetemperature in the zone is in the range of about 150 C. to about 500 C.to providean efliuent which includes, as a result of cracking, monomerscorresponding to the dimers and codimers defined above and present inthe feedstock;

(b) (i) where step (a) (i) is effected, introducing the overheaddistillate therefrom into a cracking zone wherein the temperature in thezone is in the range of about 150 C. to about 500 C. to provide aneffluent which includes, as a result of cracking, monomers correspondingto the dimers and codimers provided in step (a) (i);

(ii) where step (a) (ii) is elfected, introducing the effluent therefrominto a distillation zone wherein the temperature at the bottom of thezone is in the range of about 40 C. to about 300 C. to provide anoverhead distillate which includes monomers produced in step (a) (ii),

(c) introducing the efiluent from step (b) (i) or the overheaddistillate from step (b)(ii) into a hydrogenation zone underhydrogenating conditions, said conditions being such that the zone isessentially incapable of hydrogenating aromatic hydrocarbons, andhydrogenating said effluent or overhead distillate to provide a highoctane blending component rich in cyclic hydrocarbons having onefive-\membered ring and no more than one double bond;

wherein that (i) each of the aforementioned zones is essentiallyoxygen-free; and (ii) the residence time of the feedstock and itsderivatives in the process prior to step (c) is limited to the time inwhich no more than fifty percent by weight of the total cyclopentadieneand methyl derivatives thereof produced in the process dimerizes; and(d) recovering the high octane blending component.

BRIEF DESCRIPTION OF THE DRAWING The sole figure in the drawing is aschematic flow diagram of an illustrative embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The feedstock used in theprocess of this invention can either be the whole dripolene fractionwhich includes both the C to C fraction and the C fraction, the fractionitself, or a portion of each fraction. The feedstock can also be any oneof the components of these fractions, e.g., dicyclopentadiene, or amixture of two or more components, providing the following processrequirement is met, although, in some cases, the commercial objectivemay change in that all of the components are not useful as high octanegasoline blending components.

It has been found that the only process requirement for the feedstock isthat it contain at least five percent of at least one dimer of the groupconsisting of dicyclopentadiene or its methyl derivatives, a codimerformed from cyclopentadiene and its methyl derivatives, or a codimer ofcyclopentadiene and its methyl derivatives with conjugated dienes having4 to 10 carbon atoms. Whole dripolene generally contains at least fivepercent by weight of the dimer, dicyclopentadiene, together with thecodimer, methyldicyclopentadiene, whereas the C fraction generallycontains at least 25 percent by weight of the dimer and codimer.

The codimer formed from cyclopentadiene and its methyl derivatives is acombination of two different monomers in one molecule, e.g.,methyldicyclopentadiene is a combination of cyclopentadiene andmethylcyclopentadiene.

The codimer of the group consisting of cyclopentadiene and its methylderivatives with conjugated dienes having 4 to 10 carbon atoms is also acombination of two different monomers in one molecule, one of themonomers having a cyclopentadiene nucleus and the other monomer being aconjugated diene exemplified by isoprene, piperylene, butadiene,styrene, and indene.

Endoand exo-isomers are considered to be included within the abovedefinitions. The methyl derivatives mentioned can have 1 to methylgroups on each ring. For the sake of brevity, the term cyclopentadieneand dicyclopentadiene may be used herein to include their methylderivatives and dicyclopentadiene to include the codimers since all aresimilarly affected by the described process conditions.

A further process requirement is the use of an essentially oxygen-freeenvironment. The process, i.e., the disfilling and cracking portionsthereof, can either be conducted in the absence of air, e.g., undervacuum, or in the presence of an inert gas. Air leaks should be guardedagainst. The hydrogenation portion, of course, is conducted in ahydrogen atmosphere and so provides the necessary oxygen-freeenvironment.

The distillation zone can be provided for a conventional distillationcolumn. Columns having from five to twenty theoretical stages have beenfound suitable. Packed or bubble plate fractionating columns are mostcommonly used.

The apparatus used in the hydrogenation, other heat exchangers, refluxcondensers, pumps and various controls are also conventional.

In the distillation zone, the bottom temperature can be in the range ofabout 40 C. to about 150 C. and is preferably about 80 C. to about 140C. The pressure can be in the range of about 0.01 atmosphere to aboutthe pressure required to accommodate the maximum temperature employed,e.g., one atmosphere, and is preferably in the range of about 0.1atmosphere to about 0.2 atmosphere. Both temperature and pressure varythroughout the zone. The head temperature can be controlled, if desired;however, it is dependent on the feed and the bottoms temperature. Underusual operating conditions, it can vary from about 40 C. to about 150 C.or higher.

Referring to the drawing:

The feedstock is introduced through line 1 into distillation column 2 atabout the middle tray thereof. The temperature of the column is suchthat the light components are vaporized and pass up the column wherethey become the overhead distillate and are taken off through line 3. Aportion of the distillate is returned along line 5 to distillate column2 above the top plate as reflux. The balance of the overhead distillatewhich may -be called distillate make or make, continues along line 3 andenters cracker 6. A pump may optionally be inserted in line 3 betweenthe inlet to line 5 and cracker 6. The ratio of reflux to make in thedistillation zone is maintained in the range of about 0.1 to about 10parts by weight of reflux to one part by weight of make and preferablyabout 0.1 to about 4 parts by weight of reflux to one part by weight ofmake. The particular ratio is generally selected by the technicianrunning the process based on the particular feedstock and thetechnicians experience with same.

Returning to distillation column 2, the heavy compo nents of thefeedstock pass down the column and become bottoms. The portion below thebottom plate in column 2 acts as a kettle (not delineated) and thebottoms passes through line 7. At a point along line 7 a portion of thebottoms is removed from the system along line 9. The amount removed issimply that amount which will maintain a constant level of the bottomsbelow the bottom plate.

The balance of the bottoms passes into the tube side of heat exchanger12 which acts as a reboiler. The heating fluid passes through the shellside of the heat exchanger and can be steam at a pressure in the rangeof about one atmosphere to about ten atmospheres or other suitableheating fluid at a temperature in the range of about 50 C. to about 160C. and preferably about C. to about C. The bottoms recycle provides theheat for the distillation column, but this recycle can be omitted ifdesired and other conventional heating devices used. A pump can also beinserted in line 7 to increase the velocity of the recycle and assist inavoiding fouling in the heat exchanger and kettle. The recycle keeps therise in average bulk temperature to a minimum and provides a washingaction to keep the tube and kettle surfaces free from polymer. Thebottoms return to distillation column 2 along line 7 at a point belowthe bottom plate. Essentially any lights which had remained in thebottoms are separated at this point which may be called a vapor-liquiddisengagement section (not shown). Here, any vapor or residual lightsflash up the column to join the overhead distillate and the balance ofthe bottoms which includes naphthalene, polymers, and gum passes as aliquid into the kettle of column 2 (also called the collection vessel)where it joins the process bottoms passing down from the feedstock andthe same procedure continues with this composite mixture. It is foundthat, in addition to essentially polymer-free tube walls in the heatexchanger, the walls of the kettle are also maintained in an essentiallypolymer-free state by following this procedure.

The temperature in the kettle (which is the same as the bottom of thedistillation column) is as noted heretofore.

The balance of the condensed make proceeds, as noted, along line 3 intothe cracking zone identified as cracker 6. Cracker 6 can be anyconventional cracking device, such as a steel tube with temperature andpressure controls, heated by steam or other medium. The tempera ture inthe cracking zone can be about 150 C. to about 500 C. and is preferablyabout 350 C. to about 450 C. Cracking can be carried out in the liquidphase, e.g., in a heavy mineral oil or uncracked polymer formed, in. th:

process, or in the vapor phase, the latter being preferred. Thepreferred liquid phase temperature range is about 275 C. to 350 C., andthe residence time can be from one to sixty minutes and is preferablyfrom two to thirty minutes. The pressure in the vapor phase crackingzone can be about 0.5 to about 2 atmospheres and is preferably about 0.7to about 1 atmosphere. Residence time in the vapor phase is in the rangeof about 0.1 to about 30 seconds and is preferably about 0.1 to about 6seconds. The conditions can be adjusted as that essentially all of thedicyclopentadiene is cracked to cyclopentadiene. Residence time islimited to avoid dimerization beyond the defined limits.

The efiiuent from cracker 6, essentially depleted of dicyclopentadiene,is cooled (all or part) to a liquid in a conventional cooling device(not shown) and then proceeds, as noted, along line 8 through a pump(not shown) to join line 13 into which hydrogen gas has been introducedfrom a source, which is not shown. The hydrogen under a partialpressure, sufiicient to provide the hydrogen required to acomplish thedesired reduction in unsaturation, typically in the range of about 10atmospheres to about 7 5 atmospheres mixes with the effiuent in line 13and enters hydrogenator 14.

The effiuent provides a liquid phase containing some dissolved hydrogen.The balance of the hydrogen and possibly some effluent remains in thegas phase so that both a liquid phase and a gas phase enter hydrogenator14.

The hydrogenator apparatus is conventional and contains a conventionalhydrogenation catalyst such as palladium on an alumina support, e.g.,0.3 percent by weight palladium based on the weight of the aluminasupport. An example of the hydrogenator is a well-insulated steel tubecontaining a single bed of the aforementioned catalyst. The temperatureof the bed is measured by a concentric thermowell. The length todiameter ratio of the tube is about 2 to l to about 30 to l.

The amount of hydrogen fed is, typically, fora C fraction, about 600 to800 standard cubic feet per barrel of make (based on pure hydrogen).Excess hydrogen of up to about 20 percent or even more can easily betolerated, but must be vented.

The hydrogen, efiluent, and recycle (discussed below) are fed into thetop of the hydrogenator as shown in the drawing and the liquid effluentand recycle trickle down over the catalyst.

Another hydrogenation catalyst which can be used is a mixture of 0.5percent by weight palladium and 0.5 percent chromium on an aluminasupport (percentages based on weight of support).

The temperature in the hydrogenator is in the range of about 40 C. toabout 250 C. and preferably about 50 C. to about 150 C. depending on theactivity of the catalyst. These ranges include a temperature gradient ofabout 25 C. to about 100 C. A preferred mode of operation is to increasethe inlet temperature to maintain an effluent diene value of about 1 toabout 2 (diene value is determined by ASTM method Dl961-64).

The hydrogen used in the hydrogenator does not have to be pure oressentially pure thus the hydrogen gas can range from 100 percenthydrogen down to a mixture of about 30 percent hydrogen and up to 70percent other gases which will not detract from the hydrogenation suchas methane. A mixture containing about 70 percent hydrogen and about 30percent methane (by volume) is a good example of a mixture of gaseswhich can be used. Again venting is important.

The total pressure in the hydrogenator is about 10 atmospheres to about75 atmospheres and is preferably about 20 atmospheres to about 60atmospheres.

The feed rate of the make is about one to about ten liquid hourly spacevelocity (LHSV) and is preferably about two to about six LHSV.

The hydrogen can be fed cocurrent to the liquid flow as shown above andpreferred, or it can be fed countercurrent thereto.

As stated heretofore, the hydrogenation conditions must be such as toavoid hydrogenation of the aromatic rings, which are so important inhigh octane blending. Since the hydrogenation reaction is highlyexothermic, some means of temperature control is used to preventreaching a temperature of greater than 250 C. to 300 C. in which rangearomatic rings might be hydrogenated. Two optional means are shown inthe drawing. One means is the introduction of a diluent (source notshown) along line 19 to join line 13, i.e., the mixture of effluent andhydrogen. The diluent can be a hydrogcarbon mixture free of activeolefins such as reformate or trimethylcyclohexane. The other andpreferred means is the use of a cooled recycle of a portion of thehydrogenated product, which is pumped along line 18 to line 13. Therecycle to efiluent ratio can be in the range of about 2 parts to about10 parts by weight of recycle per part by weight of efiiuent fed intothe hydrogenator and is preferably in the range of about 4 parts toabout 6 parts by weight of recycle per part by weight of effluent. Eachof the mentioned cooling means can be used alone or together and otherconventional means of temperature control in hydrogenator 14 can beavailed of where desired.

The desired product passes from hydrogenator 14 as bottoms through line15 and into heat exchanger 16 where it is cooled. Other cooling meanscan, of course, be used here. The product then continues along line 15to pump 17 where the product is pumped to a still or storage (not shown)and a portion may be pumped as recycle through line 18 as previouslydescribed.

Where it is desired at any point of the process to meas ure the amountof conjugated dienes including cyclopentadiene present, the diene valuemeasurement can be used. Measurement is best achieved for both monomerand dimer by analysis with a high-resolution gas chromatograph.

The residence time of the feedstock and its derivatives resulting fromcracking in the process prior to hydrogenation must be limited ifpolymer and gum formation are to be avoided. The use of a continuousprocess with no delays enroute is the preferred way of maintaining lowresidence times; however, the definition stated heretofore provides themaximum time permissible, i.e., limiting the residence time to that inwhich no more than fifty percent by weight of the total cyclopentadieneand its methyl derivatives produced in the process dimerizes after beingcracked from the defined dimers and codimers. A preferred dimerizationpercentage would be no more than about 10 percent by weight. Thisdefinition allows for various delays which might occur in the process.One way to extend the process time is to bring the distillate down to atemperature of about 0 C. to about minus 10 C., which avoidsdimerization beyond the defined limits for an extended period of time.Dimerization percentages are best determined by analysis and maintainedby adjustment of process time.

As long as the process requirements discussed above are followed, manyvariations of the process can be used especially depending upon theapparatus available, e.g., a distillation column prior to that describedmay be used to initially remove some of the lights or two or morehydrogenators can be used in parallel.

The following example illustrates the invention.

EXAMPLE The equipment, steps, and conditions described in the preferredembodiment and the drawing are used in this example.

Specific conditions are as follows:

Distillation column: 16 trays. Feed to 6th tray from bottom.

Bottom temperature in distillation column: 120 C: Temperature in refluxcondenser: 10 Cd:

Pressure in distillation column: 0.1 to 0.2 atmosphere i Reflux ratio:2:1

Overhead temperature in distillation column: 100 C.:':

Composition of whole dripolene feed to distillation column:

Component: Percent by weight (i): Naphthalene 7 Dicyclopentadiene 40Methyldicyclopentadiene 9 Other components 44 Total feed 100 Feed todistillation column: 29,000 pounds per hour Make: 65 percent by weightof feed.

Feed to cracker same as overhead distillate.

Cracker temperature: 420 c.1-

Cracker pressure: 1 atmosphere Cracker residence time: seconds Feed toHydrogenator (efliuent): 16,000 pounds per hour Component: Percent byweight (:t) Cyclopentadiene 55 Dicyclopentadiene 2 NaphthaleneMethylcyclopentadiene 12 Other components 29 Dimerization in feed tohydrogenator: less than ten percent by weight.

Hydrogenator-inlet temperature: 40 Ci- Catalyst: 0.3 percent by weight(based on weight of support) of palladium on an alumina support.

Hydrogen: essentially pure at 400 p.s.i.g.

Hydrogenator-outlet temperature: 130 C.J:

Temperature differential in hydrogenator: 90 C:

Liquid hourly space velocity of feed to hydrogenator;

1.5 Recycle to feed ratio: 5 :1 Diene value: 1.5

Results: Composition of hydrogenated product:

Component: Percent by weight (i) Cyclopentene and cyclopentane 57Methylcyclopentene and methylcyclopentane 12 Naphthalene 2 Othercomponents 29 Total product 100 As stated heretofore in the definitionof invention, cracking can precede distillation rather than followingdistillation as described previously herein and in the drawing. The sameapparatus is used and the same procedure is followed for both modes ofoperation with minor variation as follows:

The initial feed is introduced into the cracking zone which is operatedin the same temperature and pressure range as cracker 6. The effluent iscooled at least partially to condense it to a liquid and then passesinto a distillation column in the same manner as the feed throughline 1. Since the effluent contains cyclopentadiene instead ofdicyclopentadiene, the bottom temperature range of the distillationcolumn can differ from the previously described distillation zone. Thetemperature range can be about 40 C. to about 300 C. and is preferablyabout 80 C. to about 200 C. The overhead distillate proceeds aspreviously described, but the cracking zone following the distillationcolumn is now omitted and the distillate goes directly to a linepreviously described as line 13 (optionally, a pump may be insertedalong this line) and into the hydrogenator where again the sameconditions prevail. The results are similar for both modes of operation.

In the above example the C s are separated by conventional fractionaldistillation and are used as blending component for automotive gasoline.

It is found that essentially all of the cyclopentadiene and its methylderivatives are hydrogenated to corresponding cyclopentenes andcyclopentanes; hydrogenation of aromatic rings is negligible; the gumcontent of the blending component after distillation is less than 10milligrams per milliliters (as determined by -ASTM D381-64). Essentiallyno fouling of the apparatus or catalyst, or foul odor is observed, andgood stability and high volatilities are achieved.

What is claimed is:

1. A process for producing a high octane blending component for gasolinefrom feedstocks containing at least five percent by weight of at leastone dimer of the group consisting of dicyclopentadiene and the methylderivatives thereof, one codimer formed from members of the groupconsisting of cyclopentadiene and the methyl derivatives thereof, or onecodimer of the group consisting of cyclopentadiene and the methylderivatives thereof with conjugated dienes having 4 to 10 carbon atomscomprising the following steps:

(a) introducing the feedstock into a distillation zone wherein thetemperature at the bottom of the zone is in the range of about 40 C. toabout 150 C. to provide an overhead distillate which includesessentially all of the dimers and codimers defined above and present inthe feedstock;

(b) introducing the overhead distillate therefrom into a cracking zonewherein the temperature in the zone is in the range of about 150 C. toabout 500 C. to provide an efiluent which includes, as a result ofcracking, monomers corresponding to the dimers and codimers provided instep (a);

(c) introducing the efiiuent from step (b) into a hydrogenation Zoneunder hydrogenating conditions, said conditions being such that the zoneis essentially incapable of hydrogenating aromatic hydrocarbons, andhydrogenating said effluent or overhead distillate to provide a highoctane blending component rich in cyclic hydrocarbons having onefive-membered ring and no more than one double bond;

wherein each of the aforementioned zones is essentially oxygen-free; andthe residence time of the feedstock and its derivatives in the processprior to step (c) is limited to the time in which no more than fiftypercent by weight of the total cyclopentadiene and methyl derivativesthereof produced in the process dimerize; and

(d) recovering the high octane blending component.

2. The process of claim 1 wherein the temperature at the bottom of thedistillation zone is in the range of about 80 C. to about C.;

the temperature in the cracking zone is in the range of about 350 C. toabout 450 C.; and

the residence time is limited to the time in which no more than tenpercent by weight of the total cyclopentadiene and methyl derivativesthereof produced in the process dimerizes.

3. The process of claim 2 wherein said process is carried out in acontinuous manner.

4. The process of claim 3 wherein the amount of dicyclopentadienepresent in the feedstock is at least 25 percent by weight thereof.

5. The process of claim 3 comprising the following additional step:

(g) recycling a portion of the overhead distillate to the distillationzone as reflux at a ratio of about 0.1 to about 10 parts by weight ofreflux per part by weight of the unrecycled portion of the overheaddistillate.

6. A process for producing a high octane blending component for gasolinefrom feedstocks containing at least five percent by weight of at leastone dimer of the group consisting of dicyclopentadiene and the methylderivatives thereof, one codimer formed from members of the groupconsisting of cyclopentadiene and the methyl derivatives thereof, or onecodimer of the group consisting of cyclopentadiene and the methylderivatives thereof with conjugated dienes having 4 to 10 carbon atomscomprising the following steps:

(a) introducing the feedstock into a cracking zone wherein thetemperature in the zone is in the range of about 150 C. to about 500 C.to provide an effluent which includes, as a result of cracking, monomerscorresponding to the dimers and codimers defined above and present inthe feedstock;

(b) introducing the efliuent therefrom into a distillation zone whereinthe temperature at the bottom of the zone is in the range of about 40 C.to about 300 C. to provide an overhead distillate which includesmonomers provided in step (a);

(c) introducing the overhead distillate from step (b) into ahydrogenation zone under hydrogenating conditions, said conditions beingsuch that the zone is essentially incapable of hydrogenating aromatichydrocarbons, and hydrogenating said effiuent or overhead distillate toprovide a high octane blending component rich in cyclic hydrocarbonshaving one five-membered ring and no more than one double bond;

wherein each of the aforementioned zones is essentially oxygen-free; andthe residence time of the feedstock and its derivatives in the processprior to step (c) is limited to the time in which no more than fiftypercent by weight of the total cyclopentadiene and methyl derivativesthereof produced in the process dimerize; and

(d) recovering the high octane blending component.

7. The process of claim 6 wherein the temperature in the bottom of thedistillation zone about 350 C. to about 450 C.;

the tempenature in the bottom of the distillation zone is in the rangeof about C. to about 200 C.; and

the residence time is limited to the time in which no more than tenpercent by Weight of the total cyclopentadiene and methyl derivativesthereof produced in the process dimerizes.

8. The process of claim 7 wherein said process is carried out in acontinuous manner.

9. The process of claim 8 wherein the amount of dicyclopentadienepresent in the feedstock is at least 25 percent by weight thereof.

10. The process of claim 8 comprising the following additional step:

(g) recycling a portion of the overhead distillate to the distillationzone as reflux at a ratio of about 0.1 to about 10 parts by weight ofreflux per part by weight of the unrecycled portion of the overheaddistillate.

References Cited UNITED STATES PATENTS 3,457,163 7/1969 Parker 208-2553,537,982 11/ 1970 Parker 208-255 3,493,492 2/ 1970 Sze 208--2553,215,618 11/1965 Watkins 208255 X 3,544,644 12/1970 Robota 260-666 A2,352,025 6/1944 Seguy 208-68 2,431,243 11/1947 Greensfelder et a1.208-68 2,953,513 9/1960 Langer, Jr 208-68 X DELBERT E. GANTZ, PrimaryExaminer I. M. NELSON, Assistant Examiner US. Cl. X.R.

v UNITED STATES PATENT @FFECE (IERTIFHCATE @i QURRECTWN Patent No. 3,788,979 Dated January 29, 1974 fl Edward G. Ceflisch, Denvil kirReed &Kenneth D.Williamson It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as show-n below:

Column 8 line 43, Claim 1 delete "or overhead distillate".

Column 8, line 7]., Claim 5 change "(g)" to (e);

I Column 9, line 25, Claim 6 delete "effluent or". Column 10, line 2;Claim 7, change bottom of the distiiiation zone" to cracking zone is inthe range of".

\ Column 10, line 17, Claim 10, change Mg)" to --(e)--.

Signed and sealed this 8th day of October 1974.

(SEAL) Attest:

McCOY M. GIBSON JRo C. MARSHALL DANN Attesting Officer Commissioner ofPatents FORM P (10-59) uscoMM 0c 60376 P69 0.5. GOVERNMENT PRINTINGOFFICE: 196. 0-366-334.

